An image intensifier is a core component of all visible spectrum night vision devices, such as ground force and pilot goggles, weapon sights, and camera systems. The image intensifier takes the low level of visible light and near-infrared light that is available at night and amplifies it to a level that the eye can see.
Light is amplified in an image intensifier according to a three-step process. First, a low light image is focused onto a photocathode, which converts the image to an electron image. These electrons are emitted into a vacuum gap. Second, the emitted electrons are accelerated through an electric field and strike an input surface of an electron multiplier, such as a microchannel plate. The microchannel plate amplifies the signal, emitting a stream of several hundred electrons for each incoming electron. The emitting electrons are sent into another vacuum space. Third, the emitted electrons are accelerated through another electric field and strike a luminescent screen that reconverts the amplified electron image into a visible image.
The reconverted visible image may be thousands of times brighter than the original visible image, allowing the user to view the reconverted image.